Safety mechanism for hydraulically operated braking systems



*r. w. VICKIYERS 1 2,095,560

Oct. 12, 1937.

SAFETY MECHANISM FOR HYDRAULICALLY OPERATED BRAKING SYSTEMS Filed June2, 1936 2 Sheets-Sheet. l

vlllflllllllw Wfll/7/////// R O T N E v W THEODORE 14/. V/cKE/as vATTOIZNLf Oct. 12,1937.

T. W. VICKERS SAFETY MECHANISM FOR HYDRAULICALLY OPERATED BRAKINGSYSTEMS Filed June 2, 1938 I Tia-E Ali 2% v v 3328 24c [7/5 4 6- 2/ 7V VI -Emmy:

Hu'n

ATTORNE Y5 2 Sheets-Sheet 2 I IN VE-N TOQ' 7715000125 14 VICKEKSPatented Oct. 12, 1937 UNITED STATES;

PATENT OFFICE SAFETY MECHANISM FOR HYDBAULIGALLY OPERATED BRAKINGSYSTEMS Theodore W. Vickers, Los Angeles, Calif.

. Application June 2, 1936, Serial No. 83.104

15 Claims.- (Cl. 303-84) 1o ating the extremely dangerous situation ofthe vehiclebeing of control in the absence of some other means to applythe brakes.

This condition is aggravated inthefcase of a leakage in the brakingsystem of a vehicle where- 15 in the brakes are badly worn and loose, sothat should leakage occur, an independent manually operable mechanicalmeans would also be in effective to properly apply the brakes, thusfailing to obviate the dangerous situation of a ve- 20 hicle out ofcontrol due to lack of braking power.

An object of the invention is to provide a safety mechanism which, inits association with a hydraulically operated braking system, functionsto insure that although a leak should occur in one 25 portion of thebraking system, other portions of the system will remainnunaiiected toprovide a corresponding portion of the total braking power formaintaining control of the vehicle.

Another object of the invention is to provide a i 30 safety mechanism ofthe above described character which can be incorporated in aconventional braking system with ease and dispatch, and without thenecessity for altering the system.

With these and other objects in view, the inven- 35 tion consists in thefollowing combinations and arrangements of elements as embodied in thefollowing specification and particularly pointed out in the appendedclaims.

In the accompanying drawings,

40 Figure 1 is a semi-diagrammatic plan view showing the safetymechanism embodying this invention incorporated in a conventionalhydraulically operated four-wheel braking system of a motor vehicle;

45 Figure 2 is an enlarged vertical sectional view preferably in theform of a casting provided with a longitudinally extending open endedbore ll closed at its ends by threaded and tubular inlet and outletplugs l2 and", respectively, coacting with the bore H to define acylinder in which -5 is reciproeably" mounted a cup-shaped piston Inormally urged to the extreme position shown in Figure 2 by a springii'abutting one end of the piston and a yieldable annular valve seat i6at the inner end of the outlet plug I2. 10

The base wall of the piston is provided axially with a port llcontrolled by a valve ill in the form of a disk fixed to one end of astem iii. The other end of this stem has fixed thereto a second valve 20also in the form of a, disk and adapted to control an outlet port 2|formed by the bore of the outlet plug. I3. The stem I9 is mounted tofreely slide in a spider 22 (Figure 7); and a spring 23 supported withinthe piston M to abut the spider and the valve for co-action 20 therewithin urging the'stem with its valves l8 and 20 to the extreme positionshown in Figure 2 wherein the valve I8 closes the by-pass port ll.Communicating with the cylinder at opposite ends thereof are transverseducts 24 and 25 con- 25 nected by a longitudinal duct 26. At thejuncture of the ducts 24 and 2B, the latter is provided with an-annularvalve seat 21 with which is adapted to co-act a piston valve 28 workingin a cylinder 29 coaxlally arranged with respect to 30 and forming anenlarged continuation of the duct 26. The outer end of the cylinder 29is closed by a plug 30 against the inner end of which abuts a cushionbumper disk 3| engaged by a plunger 32 reciprocably mounted in the bore33 of the 35 piston valve 28. A spring 34 mounted in the bore 33 co-actswith the plunger 32 and the piston valve to urge the latter to theextreme position shown in Figure 2, wherein this valve engages the seat21 to prevent flow of liquid from the inlet end of the cylinder C to theoutlet end thereof unless a certain predetermined counter pressure orresistance is set up at the outlet end of the cylinder C, all in amanner and for the purpose to be fully described in the operation of theinvention. V

Referring particularly 'to Figure 1, the invention as above described isshown incorporated in a hydraulically operated braking system includinga liquid displacement mechanism which spe- 5 ciilcally is the pedaloperated master cylinder M from which the liquid lines F and F lead,respectively, to a plurality of brake actuating devices specifically thefront and rear wheel brake cylinders B, B and B, B, through the medium 5of a T-fltting 35. One oi the safety mechanisms is interposed in eachliquid line beyond the ntting 35 so that in the normal operation of thebraking system, and with a sufiicient quantity of liquid in the system,actuation of the brake pedal will cause the piston 01' the mastercylinder to impose pressure upon the liquid in the system to efiect theflow or liquid into the inlet end of the cylinder C through the inletplug l2.

The operation of the invention is as follows:

With the brakes released under the usual return spring (not shown)associated with the shoes of each brake and loaded at from 30 to 70pounds to urge the shoes to released position, the working parts of thesafety mechanisms respectively embodied in the fluid lines F and F tothe front and rear pairs of brakes, respectively, will occupy the normalposition shown in Figure 2.

With no leaks in the system, depression of the brake pedal to apply thebrakes will first cause the flow of liquid from the master cylinder M tomove the piston I4 towards the intermediate position shown in Figure 3against the resistance oiiered at the brake cylinders B, B, B, B to theflow of the liquid. The counter-pressure thus created reacts in' thesystem from the outlet end ot the cylinder 0 through the duct 25 andduct 26 as shown by the arrows in this figure, so as to act upon andmove the piston valve 28 to the position shown in Figure 4.

Liquid from the master cylinder M now bypasses around the piston I4through the inlet end of the cylinder C, ducts 24, 25 and 26 to theoutlet end of the cylinder C and thence to the brake cylinder to effectan. application of the,

brakes.

When the pedal is released with a corresponding drop in the linepressure, the piston l4 and piston valve 28 return to their respectivenormal positions, as shown in Figure 5, and the pressure in the brakecylinders caused by the urging action of the aforementioned returnspring for the brake shoes, is exerted upon the valve I 8 against theaction of the spring 23, to open the port I! and permit the return ofliquid to the master cylinder M as shown by the arrows in this figure.

However, where the resistance or counter pressure normally created inthe system at the individual brake cylinders is suificiently reduced byleakage in either the portion of the system for the front wheel brakesor that portion of the system for the rear wheel brakes such as wouldresult from breakage or perforation of a liquid line or leakage at thebrake cylinders, depression of the pedal will cause the piston M to moveto its other extreme position shown in Figure 6. In this position of thepiston H the valve 20 will engage its seat I6 and close the port 2| soas to seal the outlet end of the cylinder C, thus preventing furtherloss of liquid from the system at the point of leakage so that theliquid will act in that portion of the system for the other pair ofbrakes to apply the latter andenable control of the vehicle to bemaintained with two wheels instead of the four wheel brakes ordinarilyavailable. It is desirable, although not necessary, that there be onesafety mechanism for each pair of brakes rather than a mechanism foreach individual brake, as equalization and safer braking are therebyprovided.

It is to be noted that should such a leak develop in the system afterthe brakes have been applied, the sudden surge of liquid in the systemwill thus cause the valve 20 to engage its seat It and close the port2|, thus cutting oil further flow of liquid in the line and maintainingapplied those brakes whose liquid line remains intact.

In reference to the piston valve 28, it will be noted that the bumperdisk 3i enables the valve to co-act therewith in providing a fluid-tightseal preventing the ingress oi liquid from the system into the airchamber formed by the bore 33 of the valve. Any leakage ofliquid intothis air chamber would increase the pressure necessary to move thepiston valve to its open position.

As will be evident, the pressure of air in the cylinder 29 around theplunger 32 will be suillcient to prevent flow of liquid-between thepiston valve and the wall of the cylinder 29. Since the pressure in thisair space is determined by the pressure in the liquid lines there willnormally be no displacement of either liquid or air into or out of thisspace. The piston valve is thus eiiectively sealed exteriorly andinteriorly to insure its positive operation in either permitting orpreventing the by-passing of liquid around the piston l4 according asthe liquid system is intact or leaking.

It is to be understood that in a broad sense the ducts 24, 25 and 28constitute a by-pass through which liquid in the line must flow in orderto effect a brake application, and that the piston valve 28 controls theinlet from the line to the by-pa'ss, whereas the piston I4 controls theoutlet from the by-pass to the line. The piston and piston valveconstitute fluid pressure responsive means, the piston l4 functioning toopen or close the outlet according as the line is intact or leaking, andthe piston valve functioning to open or close the inlet according as apredetermined resistance to liquid flow is present in the line upon abrake application or is reduced by a leak in the line.

What is claimed is:

1. In a hydraulically operated braking system of the type wherein liquidlines connect a master cylinder with a plurality of brake cylinders, acylinder having an inlet and an outlet adapted to connect the cylinderin series with a liquid line between the master cylinder and therespective brake cylinder; a piston in the cylinder normally urged toone position and movable to another position by liquid in the line whenpressure from the master cylinder is imposed thereon; means defining aby-pass connection between the inlet and outlet through which liquid inthe line must pass from the master cylinder towards the respective brakecylinder in order to effect a brake application; a second cylinder; apiston valve in the second cylinder controlling said by-pass connection;means for urging the valve to close the by-pass connection so that whenpressure from the master cylinder has moved said piston to its secondmentioned position, and less than a predetermined resistance to the flowof liquid in the line exists at the respective brake cylinder fromleakage in the line, iurther flow of liquid to such brake cylinder willbe prevented; said urging means being ineffective to maintain the valveclosed when the system is intact and the predetermined resistance to theflow of liquid in the line exists at the respective brake cylinder,whereby to permit the flow of liquid through the by-pass connection toapply the brake; and means by which the return flow of liquid can beefiected independently of the by-pass connection in order to release thebrake.

aosasco 2. In a hydraulically operatedbraking system of the type whereinliquid lines connect a master cylinder with a plurality of brakecylinders, a

between the master cylinder and the respective brake cylinder; a pistonin the cylinder normally urged to one position and movable to anotherposition by liquid in the line when pressure from the master cylinder isimposed thereon; means defining a by-pass connection between the inletand-outlet through which liquid in the line must pass from the mastercylinder towards the respective brake cylinder in order to effect abrake application; a second cylinder; a piston valve in the secondcylinder controlling said by-pass connection; means for urging the valveto close the by-pass connection so that when pressure from the mastercylinder has moved said'piston'to its second mentioned position, andless than a predetermined resistance to the flow of liquid in the lineexists at the respective brake cylinder from leakage in the line,further flow of liquid to such brake cylinder will be presented; saidurging means being ineffective to maintain the valve closed when thesystem is intact and the predetermined resistance to. the flow of liquidin the line exists at the respective brake cylinder, whereby to permitthe flow oi liquid through the bypass connection to apply the brake; anda check valve in the piston through which the return flow of liquid canbe efiected in order to release the brake. w a

3. In a hydraulically operated braking system of the type wherein liquidlines connect a master cylinder with a plurality of braking cylinders,

cause said valve to be opened by the liquid for the flow thereof throughthe by-pass connection in order to effect a brake application; saidurging means being operable to maintain the valve closed should lessthan the aforestated predetermined resistance be offered at the brakecylinder due to a leak in the line,'whereby to prevent loss of theliquid.

4. In a hydraulically operated braking system oi the type whereinliquldlines connect a master cylinder with a plurality of brake cylinders, acylinder having an inlet and an outlet adapted to connect the cylinderin series'with a liquid line between the master cylinder and therespective brake cylinder; a piston in the cylinder normally urged toone position and movable to another position by liquid in the line whenpressure from the master cylinder is imposed thereon; means r definingaby-pass connection between the inlet inder having an inlet andan outletadapted to connect the cylinder in series with a liquid line between themaster cylinder and the respective brake cylinder; a piston in thecylinder normally urged to 'one position and 'movableto another positionby'liquid in the line when pressure from the master cylinder is imposedthereon; means defining a bypass connection between the inlet and outletthrough which liquid in the line must pass from the master cylindertowards the respective brake cylinder in order to eflect a brakeapplication; valve means co-acting with the piston to control thelay-D888 connection by opening or closing the latter according as therespective line is intact or leaking; and means by which the return flowor liquid can be elected independently of the by-pass connection inorder to release the brake.

6. In a hydraulically operated braking system of the type wherein liquidlines connect a master cylinder with a plurality of brake cylinders, acylinder having an inlet and an outlet adapted to i connect the cylinderin series'with a liquid line between the master cylinder and therespective brake cylinder; a piston in the cylinder normally urged toone position and movable to another position by liquid in the line whenpressure from the master cylinder is imposed thereon; means application;valve means co-acting with the pis-- ton to control the by-passconnection by opening or closing the latter according as the respectiveline is intact or leaking; and a check valve in the piston through whichthe return flow of liquid can be effected in order to release the brake.

'7. In a hydraulically operated braking system oi the type wherein aliquid line connects a liquid displacement mechanism with'a brakeactuating device, means defining a flow course between said mechanismand the brake actuating device through which liquid must pass from themechanism in order to effect a brake application; a valve controllingsaid flow course; means responsive to brake applying movement of the liquid to cause said valve to open when the liquid line is intact so that.liquid can flow through said flow course and effect a brake application;and means for maintaining the valve closed should a leak be present inthe line, whereby to prevent loss oi-liquid.

8. In a hydraulically operated braking system of the type wherein aliquid line connects a liquid displacement mechanism with a brakeactuating device, means defining a flow course between said mechanismand the brake actuating device through which liquid must pass from themechanism in order to effect a brake application; a valve controllingsaid flow course; means responsive to brake applying movement of theliquid to cause said valve to open when the liquid line is intact sothat liquid can flow through said flow course and effect a brakeapplication; means for maintaining the valve closed should a leak bepresent in the line, whereby to prevent loss 01! liquid; and means bywhich the return flow of liquid can be eilected when the valveis'closed, in order to release the brake.

9. In a hydraulically operated braking system of the type wherein aliquid line connects a liquid displacement mechanism with a brakeactuating device, means defining a flow course between said mechanismand the brake actuating device through which liquid must pass from themechanism in order to eflect a brake application; a valve controllingsaid fiow course; means responsive to brake applying movement of theliquid to cause said valve to open when the liquid line is intact sothat liquid can flow through said flow course and effect a brakeapplication; means for maintaining the valve closed should a leak bepresent in the line, whereby to prevent loss of liquid; means co-actingwith the valve to define an air chamber; and means for sealing the airchamber against the ingress of liquid from the system so as to insurepositive operation of the valve.

10. In a hydraulically operated braking system of the type wherein aliquid line connects a liquid displacement mechanism with a brakeactuating device, means defining a flow course between said mechanismand the brake actuating device through which liquid must pass from themechanism in order to effect a brake application; a hollow piston valvecontrolling said flow course; means responsive to brake applyingmovement of the liquid to cause said valve to open when the liquid lineis intact so that liquid can flow through said flow course and efiect abrake application; means for maintaining the valve closed should a leakbe present in the line, whereby to prevent loss of fluid; a plungerworking in said valve and co-acting therewith to define an air chamber;and a sealing member adapted to coact with the piston valve when open,to prevent the ingress of liquid into the air chamber from the system soas to insure positive operation of the piston valve.

11. In a hydraulically operated braking system of the type wherein aliquid line connects a liquid dislacement mechanism with a brakeactuating device, means defining a flow course be tween said mechanismand the brake actuating device through which liquid must pass from themechanism in order to effect a brake application; a hollow piston valvecontrolling said flow course; means responsive to brake applyingmovement of the liquid to cause said valve to open when the liquid lineis intact so that liquid can fiow through said flow course and effect abrake application; a plunger working in said valve and coactingtherewith to define an air chamber; a sealing member adapted to co-actwith said valve when open, to prevent the ingress of liquid into the airchamberfrom the system so as to insure positive operation of the valve;and a spring in the air chamber co-acting with the valve and plunger tomaintain the valve closed should a leak be present in the liquid line,whereby to prevent loss of liquid.

12. In a hydraulically operated braking system of the type wherein aliquid line connects a liquid displacement mechanism with a brakeactuating device, means defining a fiow course between said mechanismand the brake actuating device through which liquid must pass from themechanism in order to effect a brake application; a valve controllingsaid flow course; means responsive to brake applying movement of theliquid to cause said valve to open when the liquid line is intact sothat liquid can flow through said fiow course and efiect a brakeapplication; means for maintaining the valve closed should a leak bepresent in the line, whereby to prevent loss of liquid; means co-actingwith the valve to define a chamber in which air is compressed inresponse to opening movement of the valve; and means for sealing thechamber against the pressure of a brake application in order to preventingress of liquid to the chamber from the system.

13. In a hydraulically operated braking system having a liquid lineconnecting a liquid displacement mechanism with a brake actuatingdevice, means for displacing liquid in a line by pressure developed atthe liquid displacement mechanism, and operable to close the lineagainst the loss of liquid or be ineilective to close the line accordingas a leak is present in the line or the latter is intact; means defininga by-pass in the liquid line adapted to conduct the liquid in eifectinga brake application; and a valve normally closing the by-pass andoperable in response to displacement of liquid by the first means whenthe liquid line is intact, to open the by-pass for the flow of liquidtherethrough in order to effect a brake application.

14. In a hydraulically operated braking system having a liquid lineconnecting a liquid displacement mechanism with a brake actuatingdevice, means for displacing liquid in a line by pressure developed atthe liquid displacement mechanism, and operable to close the lineagainst the loss of liquid or be inefiective to close the line accordingas a leak is present in the line or the latter is intact; means defininga by-pass in the liquid line adapted to conduct the liquid in effectinga brake application; a valve normally.

closing the-by-pass and operable in response to displacement of liquidby the first means when the liquid line is intact, to open the by-passfor the flow of liquid therethrough in order to efiect a brakeapplication; means co-acting with the valve to define a chamber in whichair is compressed in response to opening movement of the valve; andmeans for sealing the chamber against the pressure of a brakeapplication in order to prevent ingress of liquid to the chamber fromthe system.

15. In a hydraulically operated braking system having a liquid lineconnecting a liquid displacement mechanism with a brake actuatingdevice, a cylinder having an inlet and an outlet adapted to connect thecylinder in series with the liquid line between said mechanism and abrake actuating device; a piston in the cylinder for displacing liquidin the line by pressure developed at said mechanism, and operable toclose or open the outlet according as a leak is present in the line orthe line is intact; means defining a by-pass between the inlet andoutlet; a second cylinder; and a piston valve in the second cylindernormally closing said by-pass and exposed to counter pressure imposedupon the liquid when pressure is developed by said mechanism and theline is intact, to open the by-pass for the flow of liquid around thepiston in order to effect a brake application.

THEODORE W. VICKERS.

